A helper primitive effect for unlifting to a base monad.

Helper primitive effects are effects that allow you to avoid interpreting one of your own effects as a primitive if the power needed from direct access to the underlying monad can instead be provided by the relevant helper primitive effect. The reason why you'd want to do this is that helper primitive effects already have ThreadsEff instances defined for them, so you don't have to define any for your own effect.

The helper primitive effects offered in this library are -- in order of ascending power -- Regional, Optional, BaseControl and Unlift.

Unlift is typically used as a primitive effect. If you define a Carrier that relies on a novel non-trivial monad transformer t, then you need to make a ThreadsEff t (Unlift b) instance (if possible). threadUnliftViaClass can help you with that.

The following threading constraints accept Unlift:

• ReaderThreads

A constraint synonym for MonadBaseControl b m together with that StM m a ~ a for all a.

Run a Unlift b effect, where the unlifted monad b is the final base monad of m

Derivs (UnliftToFinalC b m) = Unlift b ': Derivs m

Prims  (UnliftToFinalC b m) = Unlift b ': Prims m

Run a Unlift m effect, where the unlifted monad m is the current monad.

Derivs (UnliftC m) = Unlift m ': Derivs m

Prims  (UnliftC m) = Unlift m ': Prims m

A valid definition of threadEff for a ThreadsEff (Unlift b) t instance, given that t is a MonadTransControl where StT t a ~ a holds for all a.

Strengthen an Algebra p m by adding a Unlift m handler

Strengthen an Algebra p m by adding a Unlift b handler, where b is the final base monad.